AgEng EurAgEng
Paper no: 98-F-072
Title:
STORABELITY OF MELON FOR DIFFERENT RIPENESS STAGES AT HARVEST. SELECTION OF INSTRUMENTAL PROCEDURES FOR QUALITY ASSESSMENT.
Authors:
Agulheiro Santos, A.C.1}; Barreiro Elorza, P.2); Ortiz C.2); Ruiz-Altisent, M.2)
1) Fitotecnia Department, University of Evora, Portugal.
Email: [email protected]
2) Physical Properties Laboratory, Rural Eng. Department, ETSIA, University Politecnica Madrid. Spain
Email: [email protected]
Summary:
The consumption of melon (Cucumis melo L.) has been, until several years ago,
regional, seasonal and without commercial interest. Recent commercial changes
and world wide transportation have changed this situation.
STORABILITY OF MELON FOR DIFFERENT RIPENESS STAGES AT HARVEST. SELECTION OF INSTRUMENTAL PROCEDURES FOR QUALITY ASSESSMENT.
Agulheiro Santos, A.C.1}
Barreiro Elorza, P.2)
Ortiz C.2)
Ruiz-Altisent, M.2)
1) Fitotecnia Department, University of Evora, Portugal.
Email: [email protected]
2) Physical Properties Laboratory, Rural Eng. Department, ETSIA, University Politecnica Madrid. Spain
Email: [email protected]
INTRODUCTION
The consumption of melon (Cucwnis melo L.) has been, until several years ago, regional, seasonal and without commercial interest. Recent commercial changes and world wide transportation have changed this situation and countries from meridional Europe have discovered that they can easily provide these fruits whenever they are able to guaranty quality.
First references on the post-harvest quality of melon come from the 80's (Andre, 1982; CEMAGREF, 1982; Dull, 1989). In these studies recommendations are given about standard destructive tests for quality assessments as Solid Soluble Content (SSC) and Magness-Taylor (MT) Firmness. There are specific performance of MT for melons and reference values for several commercial quality such as excellent (refractometric index
> 12, Magness-Taylor firmness between 0,5 and 1,5 Kg/0,5 cm") and good
(refractometric index > 9, Magness-Taylor firmness between 0,5 and 1,5 Kg/0,5 cm2).
New indications on destructive tests performed on melon come from Mizrach et al (1989), and Cardenas-Weber et al (1991), where the elasticity modulus on fruit probes are performed. Mizrach et al (1989) demonstrated that there is a strong variation of the elasticity modulus depending on the depth at which the fruit probe is extracted obtaining typical strain-stress curves for outer, middle and inner flesh of the melon. The relationship between the elasticity modulus and attenuation coefficient (r= 0,787) of ultrasonic excitation suggest that this measurements could be used for non-destructive internal quality assessment of the melon. The work of Cardenas-Weber et al (1991), on the elasticity modulus was oriented to the applicability of a gripping robot, in order to know the maximum force which could be applied to the melon without danger of bruising.
Besides the work of Mizrach et al (1991) on the non-destructive internal quality assessment of melons, new techniques as impact and acoustic impact response have been carried out on melon. Non-destructive impact have been used by our research group Agulheiro Santos (1991), Agulheiro Santos and Ruiz Altisent (1993), with good perspectives for melon ripeness assessment, based on a previous development (Chen et
peaches, apricots, avocado (Jaren et al, 1992, Correa et al, 1993, Barreiro e Ruiz-Altisent, 1993).
Acoustic impact response has been widely studied by Sugiyama et al (1994) showing a high correlation between the transmission velocity of the acoustic impact and the fruit firmness measured as penetration resistance (N) with 3 mm rod (r=0,832). Finally, in 1998 a portable prototype based on the acoustic impact response has been presented by Sugiyama et al (1998) in order to perform field measurement of the ripeness stage of melons.
OBJECTIVES
The main objectives of this work are:
• To study the main sources of variation in the mechanical, physical and chemical properties of melons during cold storage;
• To select the best tests to assess quality/ripeness
• To determine optimal ripeness stage at harvest in relation to sensory evaluation
MATERIAL AND METHODS
Fruits belonged to Cucumis melo L. cv. Gustal. A factorial design concerning ripeness stage at harvest (3 modalities) and cold storage period (7 modalities) has been used. Ripeness stages consisted of 1) a complete ripe group of fruits (41 days after anthesis DAA), 2) an unripe but very near from the ripe stage (34 DAA) and 3) an absolutely unripe (28 DAA) sample.
The fruits were stored at 6°C of temperature and 90% of R.H.. At predetermined days (3, 8, 15, 21, 27 and 31) samples were removed from cold storage and analysed. Each sample covered 4 fruits, so a total amount of 84 melons were used.
The tests carried out can be summarised as follows:
/ - Physical: Observation of external and physical characteristics such us: diameter,
length, weight and weight loss (weightl), volume, and flesh width (fleshw).
2 - Mechanical
Non destructive Impacts, a spherical mass with 47,292 g of weight indent the fruit at
the height of 12 cm. The maximum force (IMF), maximum deformation (IMD), permanent deformation, absorbed energy (IME) and impact duration (ITT) are extracted from the deceleration data registered by an accelerometer.
Compression, using a 30mm diameter sphere until 3mm of deformation are reached .
Force at 3mm is measured (CF3).
Skin Puncture, using a cylindrical rod, 0.5 mm diameter. Test is performed until a
maximum of 8 mm of penetration is reached. The maximum puncture force (PMF), the puncture deformation (PD) and the remaining force after skin rupture, named as stable puncture force (PFS), are measured.
Magness-Taylor Test, using a 8mm diameter rod, the test is performed in the mesocarp
3 - Chemical: Solid Soluble Content, in fruit juice using a refractometer at
Magness-Taylor site (Brixpar) and average fruit measurement (Brixtot).
4 - Sensory: Sensorial Evaluation with a pool of 8 people maximum trained for this
commodity (Global Hedonic evaluation).
RESULTS AND DISCUSSION
Sources of variation affecting mechanical, physical and chemical parameters
Several mechanical tests are more related to the changes that occur during cold storage than to the ripeness stage at harvest (F value in ANOVA analysis higher for "storage duration" than for "days of anthesis"). That is the case for :
• Non destructive impact: Maximum force (Fstorage=42.05), Impact duration (Fstorage=35.31)
• Non Destructive Compression : Force at 3mm (Fstorage=54.22) • Magness-Taylor firmness : Force at 3mm (Fstorage=55.28)
The loose of weight is also the physical parameter showing the highest relationship with changes occurred under cold storage (Fstorage=106.67).
The ripeness stage at harvest is mainly related to the chemical test such as Soluble Solid Content (F value for "days of anthesis" = 32.82 when compared to 3.78 for "storage duration"). Some mechanical parameters also relate mainly to the ripeness stage at harvest as the Maximum Force (MFP, Fanthesis=50.80) and the Stable Force (StFP, Fanthesis=46.10) both belonging to the skin puncture test. This is also the case for most
of the physical parameters: diameter (Fanthesis=16.12 ), lenght (Fanthesis= 11.86), volume (Fanthesis= 16.44).
The highly significant effect obtained in the interaction between "days after anthesis" and "cold storage duration" for several mechanical parameters: impact maximum force (F interaction=6.46, see first row in Figure 1), impact duration (F interaction^. 19), Magness-Taylor firmness (F interaction=9.83) and force at 8mm (F interaction=9.41), and force at 3mm deformation (F interaction=8.74) under non destructive compression, indicates a differential behaviour of melons under storage due to differential harvest conditions.
A Principal Component Analysis has been carried out using a pool of 14 physical, mechanical and chemical parameters. The first Principal Component, explaining a 43 %
of the total variance,cis composed by mechanical tests such as Maximum Impact Force
The Solid Soluble Content (SSC) is related to the Second Principal Component (24% of total explained variance) also highly independent from the parameters forming the First Principal Component as the SSC increases for higher number of days after anthesis at harvest and remains fairly constant (see second row in Figure 1).
The use of the Principal Components (PC) instead of the individual parameters allows to obtain a more smooth information of the changes occurred in the melons along the cold storage period, (compare first row in Figure 1 and Figure 3).
M
g
1 W
M
x-xi
-
1- s ^ ^ $
0 3 8 15 11 27 31 « COLO tTORAGE AT*" C
34DAA Impact Maximum Force
J i 15 2\ 21 COLD STORAGE AT S"C (Ciys}
48DAA
0 3 8 ' S COLD STORAGE >
_J_: j ±S"jJ 3ev
- L j L ~ ±SM Err.
I I 27 31 ' Mea"
X
GD — 8 7
28
6°e (Days)
DAA
0 3 8 15 21 27 31 COLD STCKAOE AT 5*C &W&Z
34 DAA Solid Soluble Content
0 3 9 15 21 27 31 COCO STORAGE AT 6" JJ»f9l
48 DAA
COLD STORAGE a! "6 C {Days) COLD STORAGE AT *6 C (Bays) COLD STORAGE AT 6" C (Days)
28 DAA 34 DAA
Global Hedonic Evaluation by consumers
48 DAA
Figure 1. Evolution of selected mechanical, chemical and sensory parameters during cold storage for 3 different ripeness stages at harvest
Selection of tests for quality assessment
The chemical test along with the skin punction are the tests enabling to establish the ripeness stage at harvest. However other mechanical test as non destructive impact and compression allow to segregate at harvest the most ripe melons (41 DAA) when compared with the others ripeness stages (34 and 28 DAA) and simultaneously to follow changes during storage.
Optimal ripeness stage at harvest in relation to sensory quality
Hedonic Evaluation above 50 in a scale 0-100 in spite of 34 and 41 DAA samples which reach 75 and 84 respectively.
The ripeness stages referred in this work as 34 and 41 DAA are therefore the most adequate to in relation to sensory quality.
Variable IMF IME ITT MTFIR MT8 PMF PFS CF3 Brixtot weightl Diameter Volume MS Effect F P-level 1 Days after anthesis 596.425 25.00407 0.00 0.000056 8.11722 0.00 4.35817 14.16550 0.00 240.3767 35.04213 0.00 160.9494 33.39626 0.00 45.64687 52.79955 0.00 2.434983 46.10055 0.00 5.92908 16.55113 0.00 37.80316 30.60918 0.00 1193.393 14.3277 0.00 9.490342 16.11985 0.00 810004.4 16.44193 0.00 2 Days of cold
storage 1003.047 42.05097 0.00 0.000198 28.77386 0.00 10.86455 35.31340 0.00 216.0179 31.49110 0.00 172.4208 35.77653 0.00 8.67996 10.04007 0.00 0.715790 13.55176 0.00 19.42381 54.22192 0.00 3.44391 2.78853 0.02 8885.087 106.6730 0.00 1.997981 3.39368 0.01 250654.6 5.08793 0.00 1x2 Interaction 154.207 6.46486 0.00 0.000024 3.53834 0.00 2.51841 8.18568 0.00 67.4349 9.83067 0.00 45.3266 9.40507 0.00 1.24907 1.44479 0.15 0.138229 2.61704 0.00 3.12981 8.73691 0.00 1.44802 1.17246 0.32 207.339 2.4893 0.00 0.652174 1.10775 0.37 37983.5 0.77101 0.68 MS Error 23.85311 0.000007 0.307661 6.859649 4.819383 0.864532 0.052819 0.358228 1.235027 83.29277 0.588737 49264.57 Degrees of freedom 145 145 145 145 145 145 145 145 62 62 62 62 Number of Observation s 166 166 166 166 166 166 166 166 83 83 83 83 Cv % 10.91 5.36 9.38 36.34 36.99 18.84 32.22 20.31 12.17 17.07 4.83 13.99
Factor Loadings
Extraction: Principal components (Marked loadings are > .700000)
Factor Factor Factor 1 2 3
IMF IMD ITT MTFIR MTD PMF PD CF3 WEIGHTL FLESHW. BRIXPAR BRIXTOT VOLUM Expl.Var Prp.Totl
0.84190846 -0.89152765 -0.89966397 0.45812293 -0.37945568 -0.34508127 -0.8430376 0.86510441 -0.81086637 0.55374117 0.30059567 0.25945111 0.50613127 5.62306408 0.43254339
-0.4769169 0.29260828 0.32256285 -0.51765256 -0.04494544 -0.64150632 -0.21135044 -0.31660942 -0.06488877 0.56097525 0.8495196 0.87011139 0.40042608 3.2015635 0.24627412
0.1126708 -0.06556573 -0.10132693 -0.24315165 0.55178512 0.34021494 0.12758529 0.13408784 0.35023255 0.39696493 -0.07992433 -0.08454277 0.58363439 1.1752625 0.09040481
-!-U J ~L
--^ r~? "1
-4^
_ 1 _ m r j L ~
• tSVEtl
• M O D
COLD STORAGE AT 6" C (Days) COLD STORAGE AT 6° C (Days) COLD STORAGE AT S» C ( Da/5)
Figure 3. Evolution of the 1st Principal Component for different days of anthesis and cold storage periods.
CONCLUSIONS
• The ripeness stage at harvest relates to the chemical properties, which also remain fairly constant even they are 31 days of cold storage.
• The mechanical properties based on non-destructive Impact and Compression can be used to monitor cold storage evolution. They can also be used at harvest to segregate the highest ripeness stage (41DAA) in relation to less ripe stages (34 and 28 DAA).
• Texture evolution along cold storage exhibit a sigmoid behavior for the three ripeness stages at harvest. The ripeness stage of 28 DAA shows the worst evolution when compared to 34 and 41 DAA.
• Only 34 and 41 DAA reach a Global Hedonic Evaluation above 50 (75 and 84 respectively) in a scale from 0-100.
REFERENCES
6.
Agulheiro Santos, A.C.. 1991. Determinacao de Caracteristicas Fisicas em Meloes 'Branco da Leziria' e 'Piel de Sapo'. Master degree, Instituto Superior de Agronomia, Universidade Tecnica de Lisboa. Portugal.
Agulheiro Santos, A.C. and M. Ruiz Altisent. 1993. Impact Test In Melon (Cucumis melo L.). Fruit, Nut and Vegetable Production Engineering. Valencia-Zaragoza, Spain.
Andre, P. et al.,1982. Essais de Conservation de Melons Cantaloup. P.H.M.- Revue Horticole, n° 227.
Barreiro, P. and M. Ruiz-Altisent. 1993. Bruise Susceptibility in Pome Fruits under Different Loading and Storage Conditions. Fruit, Nut and Vegetable Production Engineering. Valencia-Zaragoza, Spain.
Cardenas-Weber, M., R. L. Stroshine, K. Haghighi and Y. Edan. 1991. Melon Material Properties and Finite Element Analysis of Melon Compression with Application to Robot Griping. Transactions of the American Society of Agricultural Engineers (ASAE). 34(3): 121-127.
CEMAGREF, 1982. Mesure de la Qualite Gustative du Melon Type Charentais. CEMAGREF.48(1). France.
Chen, P., S. Tang and S. Chen. 1985. Instrument for Testing Response of Fruits to Impact. ASAE paper n°l 85-3537.
Storage (6°C) in different Conditions. AGENG92, Paper n° 9211-16. International Conference on Agricultural Engineering. Uppsala, Sweden.
9. Dull, G.G. et al., 1989. Near Infrared Analysis of Soluble Solids in Intact Cantaloup. Journal of Food Science, 54 (2): 393-395.
10. Garcia, C , M. Ruiz Altisent and P. Chen. 1988b. Impact Parameters Related to Bruising in Selected Fruits. ASAE, paper n° 88- 6027.
11. Jaren, C , M. Ruiz Altisent and R. Perez de Rueda. 1992. Sensing Physical Stage of Fruits by their Response to Nondestructive Impacts. AGENG 92. Paper n° 9211-13. International Conference on Agricultural Engineering. Uppsala, Sweden.
12. Mizrach, A., N. Galili, G. Rosenhouse and D.C. Teitel. 1991. Acoustical, Mechanical, and Quality Parameters of Winter-Grown Melon Tissue. Transactions of the ASAE. 34(5):2135-2138.
13. Sugiyama, J., T. Katsurai, J. Hong, H. Koyama and K. Mikuriya. 1998. Melon Ripeness Monitoring by a Portable Firmness Tester. Transactions of the ASAE. 41(1): 121-127.